The science is clear. We are at risk. Some reports overstate the risk but there is a risk. The report by the security services is said to be a "reasonable worst case scenario", so it is almost certainly overstating the risk. It is unlikely to be as bad as this report suggests. But, unless we address global warming, there will be more extreme weather, water scarcity, crop failures, etc.
Private jets are a small but growing contributor to climate change. We need the ultra rich to cut back on their use or find a way to make private jets less polluting.
Data centres are also a problem. They currently account for around 1% of greenhouse gas emissions and this is projected to rise due to the surge in AI. It is unlikely the demand for data centres will reduce, so we need to find a way to make them more energy efficient and less polluting.
Note that the movements arguing that there is no climate crisis are headed or backed by the ultra rich who benefit from things continuing as they are today, not by scientists. That should tell you everything you need to know.